Longer Immersion Research Articles

Investigation of in-situ ion release and surface film formation of hcp Mg-Li thin films

In this work, the dissolution process of magnetron sputtered Mg-Li thin films was investigated by in-situ flow cell/ICP-MS measurements and ex-situ ICP-MS measurements after longer immersion and additional XPS measurements. High Li concentrations are released due to a Li rich carbonate layer formed in air. The depletion of Li leads to preferred Mg release before preferred Li release occurs due to the higher activity of Li and incorporation of Mg in corrosion products. This data provides a baseline for developing release profiles for medical application, more generally, it unravels details of the corrosion mechanism of lightweight MgLi alloys.

Design of novel glass fiber reinforced polypropylene cable-anchor component and its long-term properties exposed in alkaline solution

The high performance and long life of engineering structures can be realized through replacing traditional steel materials with glass fiber reinforced polypropylene composites with high toughness/durability, flexibility design and recycling. In addition, the anchorage problem of composites needs to be solved by developing new anchorage technologies or forms. In the present paper, a new type cable-anchor component was developed to prolong the service life and realize the reliable anchoring of composite. The influence mechanism of arc angle (10°, 20°, and 30°) on the mechanical properties of cable-anchor component was evaluated through the experimental and mechanical simulation. The durability evolution of cable-anchor component exposed to alkali solution environment was investigated through macro-performance test and microstructure analysis. The results showed the tensile strength retention of cable-anchor component was up to 88.7 % at the arc angles of 10° under the circumferential constraint of carbon fiber. Larger arc angle increased the stress concentration and fiber misalignment of transition area between arc and straight segments, leading to the formation and propagation of defects or cracks in transition areas and early fracture failure. The saturated water absorption and diffusion coefficient of glass fiber reinforced polypropylene composites were obtained to be 0.78 % and 4.41×10−14 m2/s, respectively. Compared with nylon 6 and epoxy resin, polypropylene has excellent hydrophobic properties with the diffusion coefficient ratio of 0.0077 and 0.024. At the longest immersion, the tensile strength retentions of cable-anchor component were 61.8 % and the failure mode changed from component longitudinal splitting to brittleness fracture of arc region. The degradation mechanism was attributed to the initial defects of arc section formed and expanded under the complex stress and corrosive medium, which further aggravated the fiber/resin interfacial debonding. Through comparing with other glass fiber reinforced thermoplastic and thermosetting composites, the cable-anchor component has higher tensile strength retention after the immersion of alkaline solution owing to excellent hydrophobicity behavior of polypropylene and efficient preparation process.

Nanofibrous electrospun scaffold doped with hydroxyapatite derived from sand lobster shell (Panulirus homarus) for bone tissue engineering.

Healing of significant segmental bone defects remains a challenge, and various studies attempt to make materials that mimic bone structures and have biocompatibility, bioactivity, biodegradability, and osteoconductivity to native bone tissues. In this work, a nanofiber scaffold membrane of polyvinyl alcohol (PVA)/polyvinylpyrrolidone (PVP)/chitosan (CS) combined with hydroxyapatite (HAp) from sand lobster (SL; Panulirus homarus) shells, as a calcium source, was successfully synthesized to mimic the nanoscale extracellular matrix (ECM) in the native bone. The HAp from SL shells was synthesized by co-precipitation method with Ca/P of 1.67 and incorporated into the nanofiber membrane PVA/PVP/CS synthesized by the electrospinning method with varying concentrations, i.e. 0, 1, 3, and 5% (w/v). Based on the morphological and physicochemical analysis, the addition of HAp into the nanofiber successfully showed incorporation into the nanofiber with small agglomeration at HAp concentrations of 1, 3, and 5% (w/v). This led to a smaller fiber diameter with higher concentration of Hap, and incorporating HAp into the nanofiber could improve the mechanical properties of the nanofiber closer to the trabecula bone. Moreover, in general, swelling due to water absorption increases due to higher hydrophilicity at higher HAp concentrations and leads to the improvement of the degradation process and protein adsorption of the nanofiber. Biomineralization in a simulated body fluid (SBF) solution confirms that the HAp in the nanofiber increases bioactivity, and it can be seen that more apatite is formed during longer immersion in the SBF solution. The nanofiber PVA/PVP/CS HAp 5% has the most potential for osteoblast (MC3T3E1) cell viability after being incubated for 24 h, and it allowed the cell to attach and proliferate. Additionally, the higher HAp concentration in the nanofiber scaffold membrane can significantly promote the osteogenic differentiation of MC3T3E1 cells. Overall, the PVA/PVP/CS/HAp 5% nanofiber scaffold membrane has the most potential for bone tissue engineering.

Hygrothermal effect on interfacial properties of CFRP-steel joint modified by nanosilica

The interface between the carbon fiber reinforced polymer (CFRP) reinforcement system and steel substrates may deteriorate in service environments. This study is concerned with the effect of moisture and temperature conditions on the interfacial performance of CFRP-steel joints using neat/modified adhesive. Tensile and shear tests were conducted on both unmodified adhesive specimens and those modified with nanosilica to assess the impact of nanoparticles. Water immersion tests were carried out on adhesive specimens with different nanosilica contents to determine the water absorption law of the adhesives at different immersion temperatures. The interfacial properties of CFRP-steel bonded joints were tested before and after hygrothermal aging. The results show that nanosilica significantly influences the mechanical properties of the adhesive, as well as CFRP-steel joints. In dry conditions, tensile and shear strengths, Young’s modulus and the elongation of adhesive are improved by increasing the nanosilica content up to about 1.4 wt%. A higher content of nanosilica reduces adhesive strength and modulus, while the elongation increases continuously with nanoparticles increasing to 7 wt%. The water absorption of the adhesive is significantly influenced by the content of nanosilica. More nanosilica particles lead to slower diffusion in adhesion and smaller saturated water absorption. A high immersion temperature speeds up the moisture diffusion, resulting in a larger moisture content and a more severe degradation in adhesive performance with the same immersion duration. Hygrothermal aging can be delayed by the addition of nanosilica with low content. The interfacial properties of CFRP-steel joints, including interfacial shear strength, load capacity and plasticity, are weakened by hygrothermal aging. Changing the main failure mode from cohesive failure to interfacial debonding may occur in CFRP-steel joints due to aging. The more severe deterioration is caused by longer immersion or a higher immersion temperature. However, the addition of nanosilica can enhance the durability of the aged joints in the long run by improving the water resistance, although peak shear stress decreases when the nanosilica content exceeds 1.4 wt%. The trilinear bond-slip model of reinforced adhesive joints may be reduced to a bilinear model by hygrothermal aging. The incorporation of nanosilica helps to mitigate the reduction in fracture energy due to water immersion at normal and high temperatures.

Environmentally Benign Water-Soluble Sodium L-2-(1-Imidazolyl) Alkanoic Acids as New Corrosion Inhibitors for Mild Steel in Artificial Seawater.

Three novel natural amino acid-derived sodium L-2-(1-imidazolyl) alkanoic acids (IZSs), namely, sodium 2-(1H-imidazol-1-yl)-4-methylpentanoate (IZS-L), sodium 2-(1H-imidazol-1-yl)-3-phenylpropanoate (IZS-P), and sodium 2-(1H-imidazol-1-yl)-4-(methylthio)butanoate (IZS-M), were investigated as corrosion inhibitors. The IZSs were synthesized following the green chemistry principles, and their structure was characterized using FTIR and NMR techniques. The corrosion study results reveal that a moderate concentration of IZSs (having low solution conductivity) showed potential corrosion inhibition for mild steel in artificial seawater. At longer immersion, IZS-P forms a uniform protective film and exhibits the potential inhibition efficiency of 82.46% at 8.4 mmol L-1. Tafel polarization results reveal that IZS-P and IZS-M act as mixed types with an anodic predominantly corrosion inhibitor. The electrochemical impedance spectroscopy results signify that IZSs inhibit mild steel corrosion through the formation of an inhibitor film on the metal surface, which was further confirmed by the FTIR, SEM, EDX, and XPS studies. DFT result shows that in IZS-P, the benzylic group (-CH2-Ph) has greater electron distribution compared to isobutyl (-CH2CH(CH3)2) in IZS-L and methythioethyl group (-CH2CH2SCH3) which supported the corrosion inhibition performance at longer immersion [IZS-P (82.46%) > IZS-M (67.19%) > IZS-L (24.77%)].

What Parameters Influence the Effect of Cold-Water Immersion on Muscle Soreness? An Updated Systematic Review and Meta-Analysis.

Our objective was to determine the efficacy of cold-water immersion (CWI) on the management of muscle soreness to identify the impact of immersion time, water temperature, CWI protocol, and type of exercise on this outcome. Intervention systematic review and meta-analysis. MEDLINE/PubMed, Embase, Central, and SPORTDiscus databases were searched from their earliest record to July 30, 2020. Only randomized controlled trials that assessed muscle soreness comparing CWI and control were included. Studies were pooled in different subgroups regarding the used protocol: water temperature (severe or moderate cold), immersion time (short, medium, or longer time), CWI protocol (intermittent or continuous application), and type of exercise (endurance or resistance exercise). Data were pooled in a meta-analysis and described as weighted mean difference (95% confidence interval, P < 0.05). Athletes and nonathletes. Cold-water immersion and control condition. Muscle soreness. Forty-four studies were included. For immediate effects, CWI was superior to control regardless of water temperature and protocol, and for short and medium immersion times and endurance exercises. For delayed effects, CWI was superior to control in all subgroups except longer immersions time. This study suggests that CWI is better than control for the management of muscle soreness and water temperature and CWI protocol do not influence this result, but only short and medium immersions times presented positive effects. Aiming immediate effects, the best results suggest CWI application only after endurance exercises, while delayed effect CWI was superior both after endurance and resistance exercises.

An additively manufactured magnesium-aluminium alloy withstands seawater corrosion

Magnesium, the lightest structural metal, has inherently poor corrosion resistance. In this study, we developed a magnesium-aluminium Mg-10.6Al-0.6Zn-0.3Mn alloy, additively manufactured by laser powder bed fusion. We reveal that this alloy has a record low degradation rate amongst all magnesium alloys in practically relevant corrosive solutions, and it even withstands seawater corrosion. As tested by a number of methods, the alloy shows even more enhanced passivation with longer immersion periods. The alloy surface following immersion maintained a nearly corrosion-free appearance and was determined to have a thin aluminium-containing surface film, due to surface enrichment of aluminium from the supersaturated matrix. Aluminium enrichment near the sample surface was also observed when the sample is immersed in phosphoric acid or exposed to atmosphere at room temperature. This study demonstrates the prospects for additively manufactured ultra-lightweight magnesium structure with outstanding corrosion resistance.

Taxonomic and Functional Metrics of Ciliates and Amoeboid Protists in Response to Stream Revitalization

Tufa-depositing streams provide great microhabitat complexity and are therefore inhabited by various periphytic phagotrophic organisms such as ciliates and amoeboid protists. Recent removal of invasive plant species Ailanthus altissima (Mill.) Swinge from the Skradinski buk tufa barrier (Krka National Park, Croatia) resulted in changes in the barrier hydromorphology including the reactivation (revitalization) of dry streams. The objective of this study was to investigate: (1) the taxonomic and functional response of periphytic ciliates and amoeboid protists to stream revitalization by comparing taxonomic (i.e., abundance, species richness and diversity) and functional (i.e., functional diversity) metrics between revitalized (N) and control sites (C) during 1 and 2-months immersion period; (2) which environmental and (3) periphyton-associated factors shape the taxonomic and functional metrics and to what extent; (4) how duration of immersion affects taxonomic and functional metrics at revitalized sites. Our results showed that taxonomic and functional metrics of ciliates and amoeboid protists responded to the prevailing conditions characteristic of revitalized tufa-depositing streams: changing hydrology (occasional high flow or drought), soil drainage, and extensive inorganic matter, i.e., tufa deposition, although their responses were somewhat different. The two assemblages also showed different responses of taxonomic and functional metrics with respect to immersion duration: while the taxonomic and functional diversity of ciliates at N sites increased with longer immersion, indicating niche diversification, those of amoeboid protists hardly changed with time. Our results suggest that a comprehensive analysis of taxonomic and functional metrics of ciliates and amoeboid protists could be a good proxy for assessing revitalization of tufa-depositing streams. However, the temporal component should always be considered when conducting such studies, as the colonization processes of ciliates and amoeboid protists are quite complex, especially in tufa-depositing streams.

Electrochemical Short-Time Testing Method for Simulating the Degradation Behavior of Magnesium-Based Biomaterials

In regenerative medicine, degradable, magnesium-based biomaterials represent a promising material class. The low corrosion resistance typical for magnesium is advantageous for this application since the entire implant degrades in the presence of the aqueous body fluids after fulfilling the intended function, making a second operation for implant removal obsolete. To ensure sufficient stability within the functional phase, the degradation behavior must be known for months. In order to reduce time and costs for these long-time investigations, an electrochemical short-time testing method is developed and validated, accelerating the dissolution process of a magnesium alloy with and without surface modification based on galvanostatic anodic polarization, enabling a simulation of longer immersion times. During anodic polarization, the hydrogen gas formed by the corrosion process increases linearly. Moreover, the gas volume shows a linear relationship to the dissolving mass, enabling a defined dissolution of magnesium. As a starting point, corrosion rates of both variants from three-week immersion tests are used. A simplified relationship between the current density and the dissolution rate, determined experimentally, is used to design the experiments. Ex situ µ-computed tomography scans are performed to compare the degradation morphologies of both test strategies. The results demonstrate that a simulation of the degradation rates and, hence, considerable time saving based on galvanostatic anodic polarization is possible. Since the method is accompanied by a changed degradation morphology, it is suitable for a worst-case estimation allowing the exclusion of new, unsuitable magnesium systems before subsequent preclinical studies.

Managing the theory-practice gap in nursing education and practice: Hearing the voices of nursing students in the United Arab Emirates.

The aim of this study is to explore factors contributing to the theory-practice gap in nursing education in the United Arab Emirates. The gap between what is taught in nursing classrooms and what is practised in clinical settings creates challenges for nursing students, practitioners, managers and educators. This has important implications for the United Arab Emirates and other developing countries as their healthcare systems require a permanent nursing taskforce that is well supplied with ready to practice graduates. A qualitative descriptive approach was used, whereby 25 senior student nurses were interviewed about their perceptions of the theory-practice gap. The major theme that emerged in this study was the 'tripod of clinical practice', with three subthemes: prepared students, aware and supportive preceptors and qualified clinical faculty. The other theme that emerged was 'real life outside the simulated lab', with two subthemes: various and unfamiliar psychomotor skills and communication with real patients. The tripod of clinical practice must be achieved for quality clinical practice. Further, attention should be directed to development of skills (e.g., communicating with real patients) that are difficult to acquire while dealing with simulated patients. Nursing students need longer immersion in simulated clinical settings, coupled with experienced clinical faculty and supportive, aware and prepared preceptors.

Dealloying corrosion of anodic and nanometric Mg41Nd5 in solid solution-treated Mg-3Nd-1Li-0.2Zn alloy

The microstructure and chemical compositions of the solid solution-treated Mg-3Nd-1Li-0.2Zn alloy were characterized using optical microscope, scanning electron microscope (SEM), transmission electron microscope (TEM), electron probe micro-analyzer (EPMA) and X-ray photoelectron spectroscopy (XPS). The corrosion behaviour of the alloy was investigated via electrochemical polarization, electrochemical impedance spectroscopy (EIS), hydrogen evolution test and scanning Kelvin probe (SKP). The results showed that the microstructure of the as-extruded Mg-3Nd-1Li-0.2Zn alloy contained α-Mg matrix and nanometric second phase Mg41Nd5. The grain size of the alloy increased significantly with the increase in the heat-treatment duration, whereas the volume fraction of the second phase decreased after the solid solution treatment. The surface film was composed of oxides (Nd2O3, MgO, Li2O and ZnO) and carbonates (MgCO3 and Li2CO3), in addition to Nd. The as-extruded alloy exhibited the best corrosion resistance after an initial soaking of 10 min, whereas the alloy with 4h-solution-treatment possessed the lowest corrosion rate after a longer immersion (1 h). This can be attributed to the formation of Nd-containing oxide film on the alloys and a dense corrosion product layer. The dealloying corrosion of the second phase was related to the anodic Mg41Nd5 with a more negative Volta potential relative to α-Mg phase. The preferential corrosion of Mg41Nd5 is proven by in-situ observation and SEM. The solid solution treatment of Mg-3Nd-1Li-0.2Zn alloy led to a shift in corrosion type from pitting corrosion to uniform corrosion under long-term exposure.

Pseudomonas folliculitis: a complication of the lockdown hot tub boom? Lessons from a patient.

An otherwise fit 58-year-old male presented with a sudden-onset rash on the buttocks and tenderness under the arms and left breast. His 25-year-old son had a similar rash on his torso and tenderness around the nipples bilaterally. Both patients were apyrexial. Over the next 24 hours redness developed at the site of tenderness under the arms and around the areolae. The family had bought a hot tub 3 weeks earlier and the father and son had longer immersion in the water compared with other family members, who were not affected. On examination there were tender erythematous nodules in the axillae (Figure 1) and around the left areola (Figure 2). There was follicular erythema with pustules over the buttocks (Figure 3). The son had similar changes in the axillae and around the areolae bilaterally with papules and pustules over the back (Figure 4). Figure 1. Erythematous nodules in the axilla. Figure 2. Erythema and induration of the peri-areola skin. Figure 3. Pustules and follicular papules with surrounding erythema over buttock. Figure 4. Papules and pustules over back. After 2 days pus started to discharge from the breast nodule of the son and a swab grew Pseudomonas aeruginosa . A diagnosis of Pseudomonas folliculitis with …

Incorporation of Corrosion Effects into the Life-Cycle Analysis of AW-2017A-T4 Aluminium Alloy under Bending Moment.

The paper presents the results of fatigue tests of corroded AW-2017A-T4 aluminium alloy samples subjected to an alternating (symmetrical) bending load. Although there are a number of works describing pre-corrosion fatigue in aluminium alloys, relatively few of them concern bending fatigue effects, in some selected alloys only. Here, the AW-2017A-T4 samples were exposed to electrochemical preliminary corrosion by immersion in an electrolyte, a 3.5% solution of NaCl in water. Several variants of series of samples differing in immersion time were tested. Based on the analysis of the results obtained, Basquin’s fatigue characteristics were developed and compared to the characteristics of the material in its nominal state, which allowed for conclusions on the influence of corrosion effects. The characteristic curves show the susceptibility of the test material to corrosive processes, which results in a decrease in fatigue life along with the increase of pre-corrosion time. The samples with longer immersion duration revealed larger surface losses and widespread corrosion pits.

Effect of Water-immersion and Air-drying Period on Spontaneous Combustion Characteristics for Long-flame Coal

ABSTRACT During the mining of coal seam groups, the physical and chemical properties of the residual coal in goaf will be changed after undergoing water leaching and air-drying, affecting the oxidation characteristics of the coal. To examine the effect of the water immersion and air-drying times on the oxidative combustion characteristics of long-flame coal, this paper uses thermal gravimetric (TG) analysis and infrared spectral analysis to analyze coal samples with different immersion and air-drying times. The change in activation energy (AE), which is associated with the change in the functional groups, was analyzed for the coal-oxygen chain reaction process under coal immersion and air-drying conditions. The results show that coal samples soaked in air-dried for 10 days after water for 20 days have a lower AE (39.14 kJ/mol) than coal samples that underwent other treatment times and have a higher oxygen absorption rate and a higher tendency to undergo spontaneous combustion. According to the TG-DSC test, a range of weight loss and exothermic strengths are observed during the longest immersion and air-drying times. Additionally, during the longest immersion and air-drying times, the variations in the different functional groups are more obvious, the aliphatic hydrocarbon chain breaks and the coal rank is lower. The period of immersion and air-drying can change the spontaneous combustion oxidation characteristics of coal. After being soaked in water for 20 days and air-dried for 10 days, the coal sample was looser and the chain reaction process was accelerated, which promoted the oxidation and spontaneous combustion of coal.

Corrosion Resistance Analysis of ST37 Carbon Steel Material Using Phosphate Conversion Coating in Various Immersion Durations

Conversion coating in metal material was a method to control the corrosion. It applied in parts of car, aircraft, factory installation, and other appliances. There were three types of conversion coating: phosphate conversion coating, chromate conversion coating, and oxalate conversion coating. There were several aspects to consider in controlling the corrosion fully. This research used phosphate because phosphate conversion coating had a low corrosion rate, affordable production cost, and environmentally friendly. This research aimed to find out the corrosion resistance of ST37 carbon steel using phosphate conversion coating in various immersion durations. Therefore, the result was a breakthrough in using phosphate conversion coating for the industries. This research used the weight loss method to calculate the corrosion rate and macro photos to obtain the corrosion form during the test. This research used ST37 carbon steel with 100 mm x 30 mm x 10 mm as the specimen and phosphate with various coating durations (10, 20, and 30 minutes). Each variation had three specimens, so this research had nine specimens in total. This research calculated the daily corrosion rate for seven days using 5% NaCl as the corrosion solution. The average corrosion rate in specimens with 10 minutes duration was 1.9599 mpy, specimens with 20 minutes immersion was 1.7647 mpy, whereas specimens with 30 minutes duration were 1.3287 mpy. Thus, the longer immersion duration created a smaller corrosion rate. Also, the corrosion formed during the test was pitting and uniform corrosion.

Evaluating the Effect of WO3 on Electrochemical and Corrosion Properties of TiO2-RuO2-Coated Titanium Anodes with Low Content of RuO2

The electrochemical and corrosion characterization of Ti0.97Ru0.03O2/Ti electrodes modified with WO3 was reported. Modification of Ti0.97Ru0.03O2/Ti electrodes with WO3 was previously described as improving the effectiveness of an azo dye degradation in a photoelectrochemical treatment. Thus, the effect of WO3 introduction to oxide film on electrode surface on electrochemical behaviour and stability of the modified electrodes was investigated. Moreover, corrosion behaviour of Ti0.97Ru0.03O2/Ti electrodes modified with WO3 was evaluated with the application of potentiodynamic polarization sweep method and open circuit potential measurement. Electrodes modified with WO3 revealed higher anodic and cathodic peak currents in K4[Fe(CN)6] solution (by 35% for 6%WO3 content) indicating higher electroactive surface area and faster electron transfer reaction. An increase in WO3 amount in the oxide layer caused an increase in the number of active sites determined in Na2SO4 and most of them (more than 80%) were located in the outer and more accessible surface. The investigation of the tested electrodes at high potentials at which oxygen evolution is observed, allowed their classification in the following order showing an increase in their activity towards oxygen evolution reaction: Ti0.97Ru0.03O2/Ti < Ti0.94Ru0.03O2-W0.03O3/Ti < Ti0.91Ru0.03O2-W0.06O3/Ti. Although the electrode modification with WO3 resulted in lower resistance to corrosion in Na2SO4 solution regarding corrosion potential, corrosion current densities were clearly lower in comparison with the non-modified electrode, especially after longer immersion in the solution. ASTs showed that even a small addition of WO3 increased the lifetime of the electrodes. The Ti0.97Ru0.03O2/Ti electrode modification with WO3 seemed to be advantageous for their application in electrochemical and photoelectrochemical degradation of organic pollutants.Graphical

Protection of Aluminum Alloy 3003 in Sodium Chloride and Simulated Acid Rain Solutions by Commercial Conversion Coatings Containing Zr and Cr

The morphology, composition and corrosion properties of commercial hexafluoro-zirconate trivalent chromium coatings (SurTec® 650) deposited on chemically cleaned aluminum alloy 3003 were studied. The coatings were deposited at room temperature using different concentrations of SurTec® 650 (10, 25 and 50 vol.%) and different conversion times (90 s, 11 min and 18 min). Scanning electron microscopy with energy dispersive X-ray spectrometry, X-ray photoelectron spectroscopy and time-of-flight secondary ion spectrometry were employed to investigate the surface morphology, composition and thickness of uncoated and coated AA3003 samples. The morphology of the coating varied from uniform nodular to non-uniform and cracked; coatings were deposited at intermetallic particles and at the alloy matrix. The main constituents of conversion coatings were Zr(IV) and Cr(III) oxides; in addition to oxides, fluorides were also formed. The corrosion properties were investigated in two solutions: more aggressive sodium NaCl and less aggressive simulated acid rain. These commercial conversion coatings exhibited a good corrosion resistance but only after longer immersion in solution, i.e., 24 h. The results reveal an interesting behavior of zirconate-based coatings on aluminum-manganese alloy.

Effect of Dehydration and Discoloration Time of Ethanol, Temperature, and Dipping Time of a Preservation Solution for Dyeing on Quality of Preserved Flowers of Rose ‘Pink Aurora’

The objective of this study was to examine the proper temperature and time for treatment when using ethanol for dehydration and discoloration of Rosa hybrida ‘Pink Aurora’ bred in Korea and also for treatment of a preservation solution for dyeing to make preserved flowers of this species. For dehydration and decolorization, dipping was carried out at 25 ± 2°C for 3, 6, 12, 18, or 24 hours, and dyeing was treated at 25, 30, or 35 ° C for 6, 12, 18, or 24 hours. The most effective duration of dehydration was 12 hours, considering that the red color decolored perfectly in the H value of the Munsell value, and the yellow color grew richer as the treatment time increased. For the treatment of the preservation solution, a “C” value (indicating chroma) was higher at 35℃ in 48 hours. Flower shrinking percentage was lower at lower temperatures and with longer times of immersion. The weight was reduced by 53%–47% after longer times of immersion at all temperatures (24-hour dehydration), whereas it was reduced by 73% after 6 hours of immersion and by 68% after 24 hours of immersion at 25°C (48-hour dehydration). In conclusion, longer immersion time resulted in lesser reduction of flower weight. In consideration of the above results, the most effective condition was dehydration for 12 hours and dyeing at 25°C for 24 hours.

Bioactive glass composite for orthodontic adhesives — Formation and characterisation of apatites using MAS-NMR and SEM

ObjectivesTo study the dissolution and fluoroapatite (FAP) formation of a new bioactive glass (BAG)-resin adhesive in an acidic solution in reference to neutral solutions, using the magic angle spinning-nuclear magnetic resonance (MAS-NMR) and the scanning electron microscopy (SEM). MethodsBAG composite disks (n = 90) were prepared from, novel fluoride-containing BAG-resin. Three sample groups (n = 30) of the disks were immersed in Tris buffer pH = 7.3 (TB), neutral artificial saliva pH = 7 (AS7) and acidic artificial saliva pH = 4 (AS4) at ten time points (from 6 h to 6 months). Half of the immersed disks at each time point were crushed into a powder and investigated by the solid state MAS-NMR. SEM studies were undertaken by embedding the other half of the immersed disk in a self-cure acrylic where the fracture surface was imaged. ResultsMAS-NMR results show that the BAG composite degraded significantly faster in AS4 compared to TB and AS7. At the end of the immersion period (6 months), around 80% of the glass particles in AS4 had reacted to form an apatite, evidenced by the sharp peak at 2.82 ppm in 31P signals compared to a broader peak in TB and AS7. It also shows evidence of fluorapatite (FAP) formation, indicated by 19F signal at −103 ppm, while signal around −108 ppm indicated the formation of calcium fluoride, from the excess Ca2+ and F− especially on longer immersion. SEM images confirm higher degradation rate of the BAG composite in AS4 and reveal the impact of time on the dissolution of more glass particles. The images also indicate apatite formation around the glass particles in TB and AS4, while it forms predominantly over the disk surface in AS7. SignificanceBAG composite demonstrate smart reactivity in response to pH change which has a potential clinical benefit against demineralization and promoting remineralisation to form more stable fluorapatites.

Advanced Course in Medical Education and Research: a Leadership Program for Outstanding Graduates

Introduction: In 2009, the Hoc Mai Advanced Course in Medical Education and Research was established. The Advanced Course is designed to provide a select group of outstanding recent Hanoi Medial University (HMU) graduates with tools to introduce and lead change in medical education and research, contributing to the development of future Vietnamese health care. The aims of the program are to develop participants’ knowledge and skills in teaching, competence in spoken and written medical English, skills in research; and provide ongoing support. The purpose of this study was to explore previous participants’ (2009-2013) perceptions of the course, and impact on professional development. Methods: In 2015, an anonymous online questionnaire was distributed to 106 Course participants who had participated in both Hanoi and Sydney (2009-2013). Participants were asked to respond to closed and open ended questions. Descriptive statistics were used to analyse data. Results: Fifty six of the 106 participants (53%) responded. The Course was overwhelmingly perceived to be beneficial in helping participants with their English speaking skills. Almost half (45%) of respondents felt the course helped with their career, teaching of students (43%) and junior doctors (43%). Regarding research skills, 31% felt that participation in the course helped in completing a research project, 32% in presenting at conferences, and 22% in publishing a paper. Although participants indicated that a helpful aspect of the Course was the opportunity to network with Australian colleagues, they would like more opportunities for future collaboration, and a longer immersion program. Conclusion: Taking part in the Advanced Course has helped participants’ professional development by improving English skills, teaching skills, research skills and career progression. However, improvements are needed in terms of further ongoing assistance with research and continued contact with Australian experts.